Ethanol production from food waste at high solid contents with vacuum recovery technology

Authors: HUANG, HAIBO - University Of Illinois; Qureshi, Nasib; CHEN, MING-HSU - University Of Illinois; LIU, WEI - University Of Illinois; SINGH, VIJAY - University Of Illinois

Submitted to: Journal of Agricultural and Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/23/2015
Publication Date: 2/23/2015
Publication URL: https://handle.nal.usda.gov/10113/62175
Citation: Huang, H., Qureshi, N., Chen, M., Liu, W., Singh, V. 2015. Ethanol production from food waste at high solid contents with vacuum recovery technology. Journal of Agricultural and Food Chemistry. 63:2760-2766.

Interpretive Summary: Ethanol, an alternate biofuel, can be produced from renewable agricultural products such as corn, sugarcane molasses, beet molasses, and agricultural residues. However, production of this biofuel from corn and agriculturally produced grains and crops is not economically feasible due to the high prices of these feedstocks. To make production of ethanol economical, it is essential to use feedstocks that are available at economical prices. For this reason we identified “Food Waste” as a novel and potential feedstock and was used to produce ethanol. The prices of this feedstock are expected to be much lower than many feedstocks including corn and molasses thus reducing production price of ethanol significantly. Additionally, use of “Food Waste” would significantly reduce environmental pollution. In addition to the use of “Food Waste” for ethanol production, we developed process technologies that would further reduce the production price of ethanol. These technologies include energy efficient recovery of ethanol from the fermentation beer/broth, and reduction in bioreactor’s capital and operational costs. Development of ethanol production from such a substrate along with the novel process technologies would significantly lower ethanol prices which would benefit United States transportation industry, biofuel consumers, and the U.S. public, and would make us independent of foreign transportation oil.

Technical Abstract: Ethanol production from food wastes does not only solve the environmental issues but also provide renewable biofuel to partially substitute fossil fuels. This study investigated the feasibility of utilization of food wastes for producing ethanol at high solid contents (35%, w/w). Vacuum recovery system was developed and applied to the fermentation process to reduce the ethanol inhibition on yeast. Results showed that a high concentration of ethanol (143.7 g/L) was produced by conventional fermentation of food wastes without vacuum recovery system. By applying the vacuum recovery at 24, 36 and 48 hr of the fermentation process, ethanol was successfully removed from the fermentation broth and recovered by the following condensation step. The ethanol concentration during the vacuum fermentation was controlled below 100 g/L, thus reducing ethanol inhibition on yeast. In the end of the conventional fermentation, the residual glucose in the fermentation broth was 5.7 g/L, indicating an incomplete utilization of glucose; while vacuum fermentation allowed complete utilization of glucose due to the reduced ethanol inhibition. Ethanol yield for the vacuum fermentation was found to be 357.5 g/kg food waste, higher than that for the conventional fermentation at 326.5 g/kg food waste.